1. Field of the Invention
The invention relates generally to wind turbines and more particularly to methods, systems and apparatus for increasing the efficiency of wind turbines.
2. Description of the Related Art
Horizontal Wind Turbines (HWT) have several negatives, such as bird strikes, having the generator mounted high with blades, which increases maintenance costs, “blades noise” and “flicker,” the flicker being caused by large HWT blades passing in front of sunlight. HWT are also known for “Ice Throws, which are large build ups of ice on the blades during winter months that can be ejected at high speed and long distances causing damage or harm to people or property. Further, because of the above drawbacks of the HWT, their placement restrictions, away from populations and homes, are currently implemented around the world.
Some of the largest Horizontal Wind Turbines have a rotor diameter of 70 m and tower height of 130 m and have experienced blade disintegration where a sheered blade debris where ejected hundreds of meters risking life a property. Moreover, sophisticated safety systems must be deployed in order to cope with wind gusts of exceptional strength.
Current Vertical Axis Wind Turbines (VAWT) are typically exposed 360 degrees to the wind making only one blade or more at the optimal efficient angle towards the direction of wind causing the remaining blades to create drag. Further, current VAWT are limited to size restrictions due to cabling and guide wires and support lattices. In addition, current VAWT are inherently unstable at higher wind speed regimes.
Vertical Axis Wind Turbines (VAWT's) of the so-called Savonius type have been conceived and deployed since the early 20th century and more recently also of the so-called Darrieus and Windside and Helical blade types. However, their significantly lower efficiency compared to traditional horizontal axis turbines has apparently restricted their use in the mini-wind turbine and microturbine arenas and rooftop wind generator industry. And apparently they are not currently considered for use in large scale Mega Watt Horizontal Axis Wind Turbine industry.
Thus, there is a need for new and improved turbines that solve the problems described above.